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81 stamens. The anthers are dark purple, and open in such manner that the pollen falls between them and the pistil, somewhat as in Viola. By this arrangement both honey and pollen are protected from the depredations of insects who have no right to it. Bees, however, in forcing their tongues down to the honeyed ovary, separate the anthers and let loose the pollen, which falls upon their heads and will be brought into contact with the stigma of another flower at their next visit. Cross-fertilization is further helped by the stigmas of a flower not becoming ripe until its anthers have shed their pollen. Flowers June and July.

Name probably from the Latin Bourra, a flock of wool, in allusion to its hairy character.

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We have pond-weeds in abundance, but the Potamogetons are the pond-weeds par excellence. There is scarcely a piece of water in this country, be it river, lake, pond, canal, or intermittently dry ditch, but has one or more species growing there. The genus is a very difficult one, such as it is impossible to do more than show the general characters of here. Hooker and Bennett, in their revision of the genus, give twenty-one British species with a number of connecting sub-species and varieties. The one figured here is the Oblong Pond-weed (P. polygonifolius), with narrowly egg-shaped floating leaves, and narrower submerged leaves. All have long leaf-stalks. The floating leaves always present the upper side to the air, and are always perfectly dry. The flowers are greenish and unattractive, collected into a slender spike. Individually they consist of a four-parted perianth, four stamens, four carpels. There is a species (P. natans) with broader floating leaves and narrow submerged leaves. A broader still is P. plantagineus, with clearer leaves and more slender leaf-stalks. P. crispus, P. densus, P. perfoliatus, P.